Piston with two cupped leathers.



F. j. CHAPSAL @I A. L. E. s/MLLQT.

APPLICATION FILED MAR 26 I9I4 grs PISTON WITI'I TWO CUPPED LEATHERS.

INVENTOI 167/ A44/ w .6. @M

v@11W/Gir villes@ eomplet@ adj CHAPSAL and LFBED Loma ci perfec joints in this :.gpix

mn pipe.

To alii 'when @'25 may 20-, cem:

Be '225 known t certain new and. u" *nl mpovemeng Pistons Wih Two fup d Lenti-1ers; We o hereby desafe the @Rowing te be full, dem, m51 exacbesc -p'on of Je i311# venton, Such as W enum@ @the SJ. themft in@ which i; ppmains ts. make and us@ the. same,

Tl '.s' nii'entcn. has foi' ias cbjec: actuated by fluid pressm@ which packed means of tw@ 3951 Tieni in oste decons. eathes are amunge, in Sri-sh a, manne' throughoui; 5 e enrevtrma and no 3 in wlmi; ecion it may be, the ccuim chamber com ssd. bezween the, hm Guppy@ eathexfs ma bdy of the cyl'- 1 Whsh 'ley mme, is ai; :fd times :l such a @rassure that the. resisi pieton pmvdec with iw@ leathers is not greater iban 'hat of a. comprising but a single cupped leather@ This novel ype 0f pist@ is apha" the commi' nf fud pressure, w membes and alan to the (5011: of @om sub: of s1. diminution @if-p in tha lowe .d

@Sivan mam in 1mi driving qui: n.13; which 'n wmmuica im anni with Lowa in the. drawing* l Qu EES amiral., strek@ t@ the resistancefofjapistonl with a single cupped leather and this conditionof aalrs chamber I (previously connected with the the chamber S' which was cut olf from them. The resistance of this double cupped leather inner body O of the piston) while it establishe'scommunication with the body' of the piston'andwith the circular chamber comprised between the two cupped leathers 'and piston is thereforev equal throughout its entire travel and no matter in what direction 1 the travel may be to the resistance of a piston comprising a single cupped leather. Inv

the modilication represented in Fig. 3 the' rigidity of the assemblage of the piston and of its rod is maintained, but the supply to the circular air chamber 3 comprised between the two ycupped leathers 6 and 7 is then furnished solely by the train pipe With this object the two cupped leathers are assembled at a sulicient interval to insure that the small orifice 8 through ,which air penetrates from 'the train pipe into the circular chamber 3 shall always be comprised between the two leathers whatever the position of the piston may be. Upon the branch connecting this small oriiice '8 with the train pipe Ga non-return valve 9 is arranged; this yalve is loaded by a spring 10 adjusted in such a manner as to balance a pressure of approximately 0.100 of' a, kilogram per square cm. acting upon the valve.

When the train pipe is charged, the upper chamber S and lower chamber I are fed directly and at the same pressure as the train pipe, but with a slight retardation as regards the upper chamber, so that the piston -is displaced to the end of its upward stroke while the circular chamber 3 comprised between the two cupped leathers is charged at the same time, but at a pressure less than 0.10001z a kilogram per square cm.`

If a reduction of pressure in the train pipe and consequently in the chamber I produces the depression of the piston P with the object of applying the brakes, the nonreturn valve 9 remains closed and the circular chamber remains cut oi'l so long as the reduction of pressure in the train pipe G is ls than 0.100 of a kilogram, but as soon as this reduction of pressure exceeds this value, the pressure in the circular chamber 3 is equal at all times to the pressure leather acted upon at the rear.

in the train pipe, because there is a continuous decantation oi air. from this chamber into the chamber I around the 'cupped The resistance opposed by the piston to the move- 85 ment of descent is then reduced to that of the upper cupped leather 7 applied against the cylindrical body in which a novss by a pressure equal to the diierence of the pressures in the chambers yS and I, that is to say tothe diminution ofpressure in.y the train pipe. This resistance' is therefore the same as that of a piston with a single cupped leather. `When, owing to the operation of the distributing slide valve,i the' pressure of the equilibrium of pressure of thev air'in the chambers S and I is constantly established by the cupped leather '7 acted upon at the,

rear by the air of the chamber 3, while the piston Pascends until the moment at which the upper edge of the slide valve cuts off the admission of air to the brake cylinder.' During this upward stroke the resistance of the cupped leather- 7 is therefore m'l andv the Vresistance of the pistonisreduced to that of the cuppedleather 6 which is applied to the cylindrical body in which it moves by a pressure equal to they difference of the pressures of the chambers I and 3,'that is to say of the chambers I and During the graduationof the application of the brake, the resistance of the piston with A'two cupped leathers whose circularv chamber is supplied from thev train pipe in the conditions indicated above, is therefore reduced in both directions to the resistance of a piston with asingle leather.

Ifafter one or moreQ applications of the brakes the train pipe is rfc-charged with the object of partially or wholly` taking oil'l the brakes, the lower chamber S which had remai-ned at a pressure slightly less than that of the chamber I, is still cut oil from the, train pipe by the distributer, while the circular chamber `5 at the same pressure as the chamber .S is first of all cutoff by the non-- return valve 9` loaded by the spring adjusted for a pressure of 0.100 kilograms per square cm., so that the piston P ascends to the top ofits'stroke and consequently the distributing slide valve opens the oriiicefor the exhaust of the air lfrom `the'brake cylinder and the communication port between the recharging reservoir and the upper chamber slightly greater than the, pressure in the chamber I connected with the train pipe G. The piston P then descends until the orifice -of the lower edge of the slide valve cuts oli' communication between the recharging reservoir and the upper chamber S whose final pressure at each partial release of the brakes, is slightly greater thanthat of the chamber I. The 'same conditions obtain at 'S whose pressure increases until it becqmes @www pressed back to the end of its stroke owing to vthe more rapid recharging of the lower chamber I. v i Y vVe claim:

l. The combination withv a luid pressure cylinder, of a, piston mounted therein lieving two cupped piston rings turned ontvWardly toward the ends of the cylinder and forming with the Walls of the cylinder and piston en ,annuler hamber., and meanslopera-ble for each stroke of the piston to equalize the pressure in said chamber with the pressure in that end of the cylinder toward which the piston is moving to reduce the friction of that piston ring which is curved or turned toward such end of the cylinder.

2. The combination with uid pressure cylinder, of a piston mounted therein hay 

